In the automatic testing of electronic devices, such as semiconductors or integrated circuits (IC), special device handlers are used to place the device that is to be tested in position for testing. The electronic testing itself is provided by a large and sophisticated automatic testing system that includes a test head. The test head is required to connect to and dock with a device handler. In such testing systems, the test head is usually very heavy. The reason for this heaviness is that the test head uses high-speed electronic timing signals generated by electronic test circuits, which must be located as close as possible to the device under test. Accordingly, the test head is packaged with electronic circuits in order to achieve high speed testing of state of the art devices.
Existing systems provide a manipulator or positioner that readily and accurately moves the heavy test head in position with respect to the device handler mechanism. The user typically must move the heavy device handler or the heavy positioner in order to provide alignment. When the test head is accurately in position with respect to the device handler, the test head and device handler are said to be aligned. After the test head and the device handler have been aligned, the test head and the device handler electrical connections can be brought together, or docked, thereby enabling the transfer of test signals between the test head and the device handler. Prior to docking, the test head and the device handler electrical connections must be precisely aligned to avoid damaging the electrical connections.
In a typical operational environment that performs electrical testing of ICs, the test head is guided manually to connect delicate electrical pins to a contacting plate of the device handler, without making use of alignment guides. After the test head has been positioned in the location where the test head can be connected and docked with the device handler, the test head is locked or kept level by means of a device manipulator. This often presents problems during production testing. For instance, the position of the test head can change causing the electrical connections with the device handler to be interrupted. The device handler also can vibrate causing intermittent electrical connections between the test head and the device handler, or even causing damage to the electrical equipment.
Due to the complexity and density of advanced, sophisticated ICs, the number of connections that must be provided to the IC during testing can be very large resulting in a heavy cable that is connected to the device under test. The heavy cable provides increased weight and mass that further aggravates the problem of establishing and maintaining secure positioning between the test head and the device handler.
Special arrangements typically are provided for the heavy interconnect cable. Some proposed solutions attempt to be able to position the test head into the desired position without interference by the cable by providing flexibility in positioning of the test head without interference by the heavy cable. Such arrangements avoid interference of the cable with the freedom of movement that must by provided to the operator of the test equipment while keeping the length of the cable at a minimum to avoid negative electrical performance during testing that can be introduced as a consequence of using a long electrical path to the device under test. Such proposed solutions also must maintain mechanical stability of the combined and interlocked device handler and test head to avoid the need for mechanical counterbalancing arrangements, and the like.
Existing systems and methods of positioning the test head with respect to the device handler frequently use lead screws and sliding/rotating mechanisms of various designs that align the test head with respect to the device handler. The positioning mechanisms also frequently are aided by electrical motors that provided three-dimensional degrees of movement in addition to rotational movement of the components of the test assembly. The various motions that are provided in this manner are however difficult to control to the required degree of accuracy leading to potential damage to the device under test or the electrical pins in the test head that are typically delicate and therefore easily damaged. The use of electrical motors and the like further require extensive floor space and therefore add to the complexity and size of the test system.
Additionally, IC testing often occurs in a clean room environment. Usable space within a clean room environment usually involves considerable expense in providing the clean room environment, further emphasizing the need for test components that are simple in design and sturdy in their application. Thus, where this ability to perform device testing in clean room environment is required, complex systems needing extensive floor space adds significant expense to the systems that are required for device testing.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.